[Foundation] Set correct availability on NSValue.value(of:)
[Foundation] Set correct availability on NSValue.value(of:)

(cherry picked from commit 35a47b3a55e113fd1212485b85d808427ccf5dea)

apple/swift-corelibs-foundation,apple/swift-corelibs-foundation,apple/swift-corelibs-foundation,apple/swift-corelibs-foundation,apple/swift-corelibs-foundation